[feign]

Hi guys,

I think you need to very cautious about this. Diving while early in first trimester such as the example of MT Solomon is very different from later in pregnancy. There are hormonal changes in the first weeks of pregnancy, but no great changes in the physiology of the cardiovascular system. The cardiovascular changes as the pregnancy progresses are what is concerning for adding freediving to the equation. There is a lot of information about freediving physiology and dramatic swings in various central basic life regulating mechanisms including heart rate, blood pressure, cardiac output, gas exchange, lung volume, peripheral vasoconstriction etc. Here is a quick list of changes in physiology that are associated with pregnancy that may conflict or impact freediving.


Physiologic changes in pregnancy


Cardiovascular and hematologic:

- Increased heart rate
- Increased cardiac output
- Increased blood volume
- increased blood pressure due to increased peripheral vascular resistance
- Potentially altered venous return to the heart - due to compression of the enlarging uterus on the inferior vena cava and pelvic veins (this is why pregnant women get hemorrhoids and leg edema more commonly from increased venous pressures)
- Hypercoagulable state - increased risk of deep vein thrombosis and pulmonary embolism


Respiratory:

- Increased oxygen requirement
- Elevated diaphragm from compression of the uterus and abdominal contents
- Increased functional residual capacity of the lungs
- Increased minute ventilation
- Increased C02 sensitivity due to progesterone


Gastrointestinal:

- Increased gastroesophageal reflux due to intra-abdominal pressure and effects of progesterone
- Delayed gastric emptying after meals and slowed gut motility from progesterone


Endocrine:

- Increased basal metabolic rate with thyroid gland enlargement and increased thyroxine hormone production
- Adrenal gland produces more cortisol throughout pregnancy


Likely very little research in the area of pregnancy and freediving has been done, but I think manipulating an already compensating cardiovascular system in a pregnant female (particularly as the pregnancy progresses) could potentially have detrimental consequences for the baby or mother.

lee